Abstrac. Here we describe synthesis and Flash Vacuum Pyrolysis (FVP) of ethyl-3-oxo-(1h-1,2,4-triazol-5-ylamine) propanoate (1). FVP reaction were carried out between 300and 480ºC, contac times of 10-2s. Reaction products at 450ºC were: ethyl-3-(3-amine-1H-1,2,4-triazol-1-yl)-3-oxopropanoate (2) and 5-hydroxy-[1,2,4]triazolo-[1,5-a]pyrimidin-7(4H)-one (3).